Reflector unit and method of making said unit



June 9, 1942. J. c. HAG GART, JR

REFLECTOR UNIT AND METHOD OF MAKING SAID UNIT Filed July 5, 1940INVENTVOYR J'omv (3 654663487, fe.

ATTORNEY atet june 9 I This invention relates to the art ofautocollimating reflecting units and especially reflectors whichcomprise a number of individual reflecting elements integrally joined toform a composite-reflecting area. Such reflectors are usually in theform of discs of glass or plastic material with the individualreflecting elements so closely emaciated that the eifect is that of asingle large reflector. These elements may be of the lenseflector typeor they may be of the a hole 'in which the unit is inserted. Thestandard includes a backing member to hold the unit in place.

The problem in connection with the assembly of the reflector and itsholder is to obtaina permanent moisture tight seal and avoid theproduction of strains which will warp the reflector and impair itsefficiency.

As is well known these reflectors are provided with a. rearwardlyextending flange which sits in the cup-like holder and isperipherallyclamped between the bottom of the holder and a turnedoverlip or flange. The production of this clamp.- ing engagement isaptto'create a radial stress which will warp the disc. I have discloseda way to avoid this in my prior Patent No. 2,255,748

- issued September 16, 1941, the principal feature which is theprovision of a clearance between the flange of the cup and the peripheryof the disc. In that construction the center of the bottom of the cup israised and fits into the disc flange, thereby centering the disc withrespect to the cup flange, and the gasket receiving annular portionsurrounding the raised center is flat. In the assembly the cup flange iscrimped over the gait, n, warmers, is. a; ta service Ccrperation, aaeration or 5, 19%, Serial No; 343,995

(case-rs) In accordance with the present invention the cup member is'sopreliminarily shaped that a resilient force is created duringtheassembly These are cup-shaped which operates to bias the turned overedge of the cup flange toward the shoulder and reactively to cause thecup to bear especially-against the gasket at the inner comer of thereflector flange and thus effect a tight seal.

More particularly the annular gasket receiving part of the holder isformed with a downward and outward inclination so that as it is drawn upinto the plane of the rear face'of the disc flange it bends about theinner corner of the reflector flange and is held there against .itsresilient reaction by the engagement of the turned over edge or lip 'ofthe flange with the shoulder. lhe opposing forces are-therefore betweenthe corner which constitutes the fulcrum and the shoulder.

As a consequence the maximum compression of the gasket is at the comer.

I shall now describe the method with particular reference to theconstruction and steps illustrated in the accompanying drawing and shallthereafter point out the invention in claims.

Fig. 1 is a cross section of the component elements at the flrst stageof the assembly.

Fig. 2 is a similar view at an intermediate stage. Fig. 3 is a similarview at the completion of the operation.

- Fig. 4 is a plan partially in section of the completed unit.

shouldered front edge of the disc and the flnal compression is obtainedby closing down the surrounding bead.

While this method practically eliminates the formation of warpingstresses, it has been found that the permanence of the seal is notentirely reliable. This invention therefore contemplates a modificationof that method.

The reflector I is a disc of plastic or other glass like composition,slightly meniscus in form.

and is shown as having tetrahedral formations on its rear face of theconstruction disclosed in the Stimson Patent No. 1,807,350. For mountingpurposes it is provided with a rear flange 2 that has a circumferentialextension beyond vthe boundary of the reflecting surface forming a frontshoulder 3.

The holder is a metallic cup member 4 the diameter of which is somewhatgreater than that of the reflector. As initially formed it has asurrounding flange 5 that joins the bottom by a projecting bead 6. Thecenter part I of the bottom of the holder is raised and is joined by aflaring neck portion 8 to the surrounding annular portion 9. The partsare so proportioned that the raised center with its flaring neck portionfits up into the back of the reflector and centers it, the inner cornerof the reflector flange op-.

posing the bottom of the neck. Theannular portion a is initially formedat a substantial inclination to the general plane of the unit, as shownin Figs. 1 and 2.

sults in anniform production.

I l. The-method of making a 'dered peripheral flange of the-reflector isresil- -iently held between the annular portion of the overlaps the neckportion 8, the outer diameter being such that it just fits within theflange 5, and is thereby centered as shown in Fig. 1. The reflector I isthen placed centrally into the holder l in which position theinner edgeof its flange face rests upon the gasket near its inner edge.

1 A forming die (not shown) of proper shape is brought to bear uponthe-top edge of the flange 5. The axial movement of this die toward thereflector crimps the edge over to form the lip 50 overlying the shoulder3. This movement in opposition to the backing member for the holder.

first brings the lip into contact with the shoulder and from that pointfurther movement, as it continues to turn over the flange .5, forces thereflector down, compressing the gasket at the line of contact. Thisconditionis illustrated in Fig. 2. Continued movement of the diesubstantiallyflattens the portion 9 againstthe backing member andcompletely centers the. reflector flange at the base of the neckportion. Meanwhile the lip 5a is caused to follow theshoulder 3 and isflattened until its inner periphery is adjacent the axial wall of thereflector forming the inner terminus of the shoulder. This is the flnalcondition as illustrated in Figs. 3 and 4.

' The gasket I is probably under more or less equal compression at theterminal movement of the die, but there is bound to be a slight springback leaving the portion 9 at a slight inclination.

. This spring back only that allowed by the lip a which is bent past itspoint of elasticity and is set. at substantially the flnal angle. Whilethe gasket Ill is under substantial compression throughout, the momentabout the angle of the stantial inclination to a plane perpendicular toflange 2 causes the reaction of the shoulder 3 on the lip 5a to urge thebottom of the holder against the gasket at the line of turning andtherefore accentuates the compression on that line. As a .consequencethe seal has proven to be satisfactory and this method of assembly re-It willbe understood that the component steps 1 of the method may becarried out in a manner other than that precisely described without de-'parting from the scope of ,the invention as pointed out in the followingclaims. I claim:

reflecting unit,

portion surrounding the raised. center at a substantial inclination to aplane perpendicular to the axis of the'holder so as to form the frustumof a cone with the base at the other periphery, seating 'the reflectorcoaxialiy within the holder with the rearface of the reflector flangeopposing the said inclined annular portion of the holder and resting atits inner edge upon the said flaring neck portion, exerting a combinedaxial and radial force upon the outer edge of the holder flange inopposition to a backing member until the flange is turned over intoengagement with the front face of the radially shouldered peripheralflange of the reflector, and then continuing the axial force until theinclined annular portion of the holder is brought into substantialparallelism with the rear face of the reflector flange to .put the saidannular portion of the holder and the turned over flange thereof.

2. The method of making a reflecting unit comprising forming a,reflector having a rearwardly extending peripheral flange radiallyshouldered on its front face, forming a cupshaped metallic holder with araised center having a flaring neck portion-and with the annular portionsurrounding the raised center at a subthe said overlapping part of thegasket, exerting a combined axial and radial force upon the outer edgeof the holder flange in opposition to a backing member until the holderflange is turned .over' into engagement with the. front face of theradially shouldered peripheral flange of the reflector, and thencontinuing the axial force upon the turned over holder flange and thereflector flange until the said annular portion. is brought intosubstantial parallelism with the rear face of the reflector flangethereby flexing the holder at the line of bearing of the inner edge ofthe reflector flange and putting the said annular portion of the :holderunder tension so that the reflector flange and the gasket areresiliently'held under substantial compression between the annularportion of the holder andthe turned over flange thereof.

3. The method of making a reflecting unit comprising forming a reflectorhaving a rearwardly extending peripheral flange radially shouldered onits front face, forming a cupshaped metallic holder with a raised centerhaving a flaring neck portion and with the annular portion surroundingthe raised center at a substantial inclination to a plane perpendicularto the axis of the holder so as to form the frustum of a cone withthe-base at the outer periphery and with the wall folded back at thejuncture of said outer periphery with the flange of. the holder to forma-peripheral bead, laying an annular gasket in the holder on the saidinclined annular portion and partially overlapping the said neckportion, seating the reflector coaxially within the holder upon thegasket with its periphery spaced from the holder flange and with theinner edge of the rear face of the reflector flange upon the saidoverlapping part of the gasket, exerting a combined radial and axialforce upon the outer edge of the holder flange in opposition to abackingmember until the holder flange is turned over into engagement with thefront face of the radially shouldered peripheral of the inner edge ofthe reflector flange and putting the said annular portion of the holderunder tension so that the reflector flange and the gasket areresiliently held under substantial compression. between the annularportion of the holder and the turned over flange thereof.

4. The method of making a reflector unit comprising forming a reflectorhaving a rearwardly extending peripheral flange radially shouldered onits front face, forming a cup-shaped metallic holder with a raisedcenter and an annular portion surrounding the raised center'at asubstantial inclination to a plane perpendicular to the axis of theholder so as to form the frustum of a a cone with the base at the outerperiphery, seating the reflector coaxially within the holder with theinner edge of the reflector flange resting upon the said inclinedannular portion, applying an axial force to the reflector and the holderto flex the said annular portion thereof at the line of contact with theinner edge of the reflector flange and put it under tension and bendingthe outer end of the holder flange overinto engagement with the outerface of the reflector flange to maintain the annular portion in itsflexed position so thatthe reflector flange is resiliently held betweenthe annular portion of the holder and the turned over flange thereof.

5. A reflector unit comprising a reflector element having a rearwardlyextending peripheral flange radially shouldered on its front face, and acup-shaped metallicholder, said holder comprising a peripheral flangewith its outer end turned inwardly into engagement with said shoulder, araised center fitting within the rearwardly extending reflector flange,and an annu-' plane perpendicular to its axis, thereby creating icomprising a reflector'element provided with a rearwardly extendingperipheral flange radially shouldered on its front face, and a metalliccup member the bottom of which has a raised center and a surroundingannulus inherently conical in shape with the base of the cone at itsouter edge, the cup member being applied to the reflector element withthe peripheral flange seated in the annulus and the flange of the cupmember turned down on the shoulder to an extent to flex the annulusabout the inner edge of the peripheral flange and bring the annulussubstantially in a plane perpendicular to its axis, thereby creating amoment about the inner edge of the peripheral flange and causing thereaction of the turned over flange andv the shoulder to urge the annulusinto close engagement withsaid inner edge.

7. As an article of manufacture a reflector unit comprising a reflectorelement provided with a rearwardly extending peripheral flange radiallyshouldered on its front face, an annular gasket, and a metallic cupmember the bottom of which has a. raised center and a surroundingannulus inherently conical in shape with the base of the cone at itsouteredge,- the cup member being applied to thereflector element withthe peripheral flange seated on the gasket in the annulus and the flangeof the cup member turned down on the shoulder to an extent to flex theannulus about the inner edge of the peripheral flange and bring theannulus substantially in a a moment about the inner edge of theperipheral flange and causing the reaction of the turned over flange andthe shoulder to substantially compress the gasket between the annulusand ripheral flange.

JOHN C. HAGGART, JR.

